Cataract is a condition that creates cloudiness in the lens of an eye, and is one of the major causes of blindness in the developing world. Cataract occurs in the lens of an eye and impedes the lens from focusing light on the retina. The lens is composed of tightly packed lens fibers surrounded by a collagenous elastic capsule. Beneath the lens capsule are epithelial cells, which are responsible for the metabolic function of the lens. Cataract may occur in any or all of these parts of the lens, which results in several different classifications of cataract, namely, subcapsular, cortical, and nuclear. To treat cataract, the cloudy portion of the lens, whether it is in the lens fibers, the epithelial, or both, or in any other portion of the lens, should be surgically removed. Generally, this is attempted by making an incision in the corneal periphery (limbus) to enter the anterior chamber and remove the cataract.
A conventional method for removing cataract in the eye is the (manual) extracapsular technique. In this procedure, the eye is opened at the limbus, and either a bent needle or any other curved sharp edged instrument or special forceps are employed to open the anterior lens capsule and remove the nucleus within the capsule of the lens. Thereafter, the remaining cortical material is removed so as to leave a clear posterior lens capsule in the eye. The capsule provides a barrier between the anterior chamber and the vitreous cavity of the eye, as well as a resting surface for an implanted artificial lens. However, this method results in an incision of about 7 millimeters being made, thus creating an open system in the lens capsule. In other words, this method makes any fluid that is irrigated into the lens capsule difficult to retain and remove.
Other types of cell removing techniques, such as phacoemulsification, use a probe containing an ultrasonic wave generator, a rinsing fluid and a suction tip. In the phacoemulsification technique, an incision is made in the cornea of an eye and the probe is inserted. Compacted proteins of the lens nucleus are broken up by ultrasonic power and are emulsified by a rinsing fluid. The emulsified lens proteins as well as soft peripheral lens proteins are removed from the eye by the suction tip. Phacoemulsification is generally considered superior to extracapsular surgery because it only requires a surgical wound of about 2–3 millimeters as opposed to about 7 millimeters. However, the problem with phacoemulsification is that opacification of the remaining capsule or posterior capsular opacification can occur. This opacification is caused by proliferation of the remaining lens epithelium, which this procedure has failed to remove from the remaining capsule entity. An example of this type of technique is disclosed in U.S. Pat. No. 6,066,138 to Sheffer et al., the entire contents of which are incorporated herein by reference.
Several similar techniques exist for treating and removing cells in the body using an aspirator and/or an irrigator. For example, numerous types of devices use a high-pressure water jet to remove plaque deposits from the arterial walls of a patient.
Generally, these techniques use a tube with a high-pressure water jet, an evacuation tube, and a balloon. The balloon is inflated within the blood vessel to hold the tube in the desired position adjacent a plaque deposit. The water jet then ablates the plaque, and evacuates the ablated plaque through the evacuation tube.
Although these conventional systems may be useful for removing tissue in a blood vessel, they are generally ineffective for removing cells in the eye. Specifically, the balloon in the conventional systems does not assist in removing cells or help in killing the cells to impede cell multiplication. Additionally, the balloon's purpose in the existing apparatuses is to hold the device in place, thus making the movement of the device difficult and less effective for removing cells from inside a lens capsule. Examples of these types of techniques are disclosed in U.S. Pat. No. 4,911,163 to Fina; U.S. Pat. No. 5,290,295 to Querals et al; U.S. Pat. Nos. 5,370,609, 5,496,267, and 5,785,675 all to Drasler et al; U.S. Pat. No. 5,439,446 to Barry; and U.S. Pat. No. 5,514,092 to Forman et al., the entire contents of each are incorporated herein by reference.
Thus, there is a continuing need to improve the systems and methods for removing cataract and preventing unwanted cell proliferation in the eye.